Ingo Arndt / Christmas Island Red Crabs (Gecarcoidea natalis) crossing closed road, during annual migration, Christmas Island, Indian Ocean, Australian Territory, November 2009.

Thomas Mangelsen / Polar Bear (Ursus maritimus) mother and cub crossing ice field, Churchill, Manitoba, Canada

Adrian Davies / Amphibian crossing sign. Sintra, Portugal. April 2019.

Philippe Clement / Eurasian otter / European otter (Lutra lutra) road warning sign for otters crossing street in coastal Scotland, Shetland, UK

Philippe Clement / Eurasian otter / European otter (Lutra lutra) road warning sign for otters crossing street in coastal Scotland, UK

Adrian Davies / Sign warning drivers of Red squirrel (Sciurus vulgaris) crossing, Re-introduction project, Torridon, Scotland, UK. May 2018.

Adrian Davies / Sign warning drivers of Red squirrel (Sciurus vulgaris) crossing. Re-introduction project, Torridon, Scotland, UK. May 2018.

Franco Banfi / Black bear crossing warning sign, Juneau, Alaska, United States.

SCOTLAND: The Big Picture / Sign erected alerting drivers to red squirrels crossing road, Shieldaig, Wester Ross, Scotland, UK.

Martin Gabriel / Caution sign 'Sousliks crossing the road', European souslik (Spermophilus citellus), Lake Neusiedl, Austria, April.

Juergen Freund / Caution sign which reads : Slow down Brolgas crossing here, Northern Territory, Australia.

Donald M. Jones / Rocky Mountain Elk (Cervus canadensis nelsoni) bull crossing train tracks, North America